Steam heating system for aircraft



Sept. 24, 1940.

.1. VAN VUL PEN ET AL 2,215,517 1 STEAM HEATING SYSTEM FOR AIRCRAFT Filed April 8, 1

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' llznwpei 1 I Ru] 12227 8 P!- 24, 1940- J. VAN VULPEN ET AL. @2 5" STEAM HEATING SYSTEM FOR AIRCRAFT Filed April 8, 1939 2. Sheets-Sheet z lll l I I'HIJHIIIHI'III IH I I I 10' 19 I i 9 17 r I J 1/ 4 i l v I tzi .77 41 70 21522 %n% e22 Paul .5 Parks 4 a Patented Sept. 24, 1940 Y UNITED STATES PATENT. OFFICE STEAM HEATING SYSTEM FOR AIRCRAFT New York Application April 8, 1939, Serial No. 266,718

14 Claims.

5 tially constant supply. of excess heat which maybe used for converting water into steam or vapor.

In airplanes or other apparatus utilizing an internal combustion engine, there is available, when the engine is operating, a continuous flow of highly heated exhaust gases which are usually vented through the exhaust pipe with a consequent loss of the heat remaining in these gases. In a heating system of the type herein disclosed, a small steam generator is so constructed as to hold a relatively small quantity of water in intimate relation to the highly heated exhaust pipe so that this water will be flashed into steam. The water in the generator is continuously replaced and vaporized, and the steam is conducted through one or the other of. a pair .of similar radiators where it is condensed, the heat being transferred from each radiator to an air stream in the path of which the radiator is positioned. The condensate from each radiator drains back into a tank or reservoir from which the water flows into the lower portion of the generator to renew the supply therein. This circulation of fluid is continuous as long as the engine is in operation. The air stream flowing over one of the radiators is delivered into the compartment or space that is to be ventilated and heated. The air stream flowing over the other radiator is dissipated into the outer air. Electrically operated means controlled by a thermostat in the space to be heated is adapted to direct the steam from the generator alternatively through either one of the two radiators. In this way the steam is always being condensed at a steady rate to maintain the continuouscycle in the steam system, but the air stream that is being constantly delivered into the compartment will only be heated at such times as is necessary to maintain the desired temperature within the compartment.

The general object of this invention is to provide an improved heating system of the type Another object is to provide an improved thermostatic control system for the heating and ventilating apparatus.

Other objects and advantages of this invention will be more apparent from the following detailed, description of one approved form of apparatus .constructed and operating according to the principles of this invention.

In the accompanying drawings:

Fig. 1 is' a perspective, partially diagrammatic 10 view of the principal elements of the heating and ventilating system.

Fig. 2 is a transverse vertical sectionthrough the generator and supply tank.

. Fig. 3 is a wiring diagram of the electric control system.

Referring first to Fig. 1, streams of air are constantly forced through the two similar conduits A and B, the stream from conduit A being discharged through outlet I and wall 2 into the space or compartment 3, here indicated as'being partially enclosed by walls 2 and 4. The air stream flowing through conduit B is discharged through the deflected end portion 5 which leads at any convenient point intothe outer air. When installed on an airplane, outside air will be continually forced into the inlets 6 and '1 of the respective conduits by a suitable scoop device and the rotating propellor. Ifnot used on a moving vehicle such as an airplane, a motor-driven blower C may be used for forcing thestreams of air through the conduits. If desired, a portion of one or both of the air streams may be recirculated 4 air withdrawn from compartment 3. At D is indicated a suitable thermostat installed in compartment 3 so as to respond to temperature conditions therein. This thermostat and its operating connections are further indicated in Fig. 3 and will be hereinafter described.

At 8 is shown a section of the exhaust pipe through which the products of combustion are vented from the internal combustion engine. This pipe 8 becomes very highly heated when the engine is in operation, but all of this heat is normally wasted. Thesteam heating system according to the present invention derives its primary heat from this exhaust pipe 8, the system including the generator or vaporizer E, the two similar. radiators or condensing units F and F, the electrically controlled inlet valves G and G for the radiators F and F, respectively, the water tank or reservoir H, and the piping connecting these elements in a continuous loop system, as will be hereinafter'described. The radiators F and F" are positioned in the respective conduits A and B 1 so that the air streams flowing through these conduits will extract heat from the radiators and condense the steam therein. The control valves G and G are indicated in section, in Fig. 3 and will be referred to hereinafter in more detail.

The generator or vaporizer E (see also Fig. 2) is so constructed as to fit closely about a section of the exhaust pipe 8 and utilize heat from the pipe and the exhaust gases flowing therethrough for generating steam. The generator here shown is of the type disclosed and claimed in the patent to Van Vulpen 2,090,013, granted August 17, 1937. This generator is of the saddle type so as to be easily positioned on or removed from the pipe 8 and comprises an inner U-shaped shell 9 adapted to rest upon the exhaust pipe 8 and a simileEr outer shell l0 spaced from theinner shell so as to form a U-shaped compartment comprising an upper steam space H and a pair of downwardly extending side legs l2 and I3 which are normally filled with water. It will be understood that the inner and outer shells 9 and ID are connected by end walls I 4, and the legs [2 and I3 are closed at thebottom so as to completely enclose the steam-generating chamber. The space between the lower portions of the legs I2 and I3 is preferably filled with insulating material I supported by the removable bottom wall I8 held in place by straps I! or other suitable securing means. lead into the bottom portions of legs l2 and I3, respectively, so as to supply water thereto and keep this water up to a predetermined level, such as indicated at a, this level being determined by the corresponding water level in the supply tank H (see Fig. 2) as will be hereinafter described. It will be noted that only the upper portions of the bodies of water in the respective legs l2 and 13 are in intimate contact with the highly heated exhaust pipe 8, and the heat at this location is so intense that these relatively small bodies of water will be very quickly flashed into steam. The relatively cold water that enters the lower portions of the legs through inlet pipes I8 and I9 is at first spaced from the heating pipe 8 by insulation 15 but gradually rises toward the pipe,

thus pre-heating the water before it comes in contact with the hot exhaust pipe and is flashed into steam. By holding the water level at the desired height, the quantity of water in contact with the exhaust pipe and the rate of evaporation may be controlled to suit the requirements, and undesired super-heating oi the steam will be prevented. It will be understoodthat this generator is of relatively small capacity.

A perforated dry-plate is preferably positioned horizontally of the upper portion of steam chamber II, the purpose of this plate being to permit the upward passage of steam to and through outlet 2| but prevent any appreciable quantities of water from rising above this plate in case bubbling or violent boiling takes place wi hin the generator.

The steam flows from generator E through outlet 2| and pipe 22 to the T-fltting 23 from which extend the similar branch pipes 24 and 25.

A pair of water inlet pipes l8 and I 9' either to radiator F or to radiator F, but to only one of these radiators at any one time.

After steam has been condensed in radiator F and has given up the greater portion of its heat to the air stream flowing through conduit 13, the resultant condensate drains out through pipe 28. check valve 21, pipe 28, T-fitting 29, and pipe into the supply tank H.- Similarly, when the steam is being condensed in radiator F, the condensate will drain out through pipe 8|, check valve 32, and pipe 83 to the fitting 29, and thence, as before, into the supply tank H. Since the two radiators or condensers F and F are of the same capacity and are connected in parallel in the steam circulating system, and since the steam is delivered to only one of these condensers at any one time, it will be apparent that the steam vaporizing-and condensing system will operate continuously and uniformly as if there were only one radiator or condenser in the system. The check valves 21 and 32 function to prevent any back flow of steam through the radiator which is not in service.

The supply tank H is provided with a lowpressure release safety valve or vent 34 so that the entire system will normally be under substantially atmospheric pressure. A pipe 35 leads from the bottom of supply tank H through cutofl valve 36 to the T-fltting 31, from which pipe 38 leads to the T-fltting 39. Generator inlet pipe 19 leads from fitting 39, and pipe 48 also connects this fitting with the other inlet pipe I8. Since valve 36 is normally open, the water will normally seek the same level in the supply tank and generator. A drain pipe 4| leading from fitting 31 and provided with normally closed valve 42 permits the water to be drained from the heating system if desired.

The required amount of water for the system is poured into funnel 43 at the upper end of filling pipe 44 leading into the top of supply tank H, and provided with normally closed valve ll. By opening the normally closed valve 48 in a drain pipe 41 leading from one end of tank H at the desired water level, the water poured into the tank may be drained out down to this predetermined level, thus determining the normal water level in the tank and boiler.

It will now be understood that the same small quantity of water is being continuously vaporized in generator E, condensed in one or the other of the radiators F or F, and then returned through supply tank H to the generator. It should be understood that the parts of this system are all relatively small and the system requires only a very small amount of water. When properly designed and adjusted, the rate of production of steam in the generator E will be just about sufiicient to supply the amount of steam that will be condensed in radiator F or .F' and only condensate flows back through pipe 30 into the supply tank H. This heating system is very simple, there being no controls whatever other than those provided formaintaining the desired water level. This water level need only be tested and adjusted at long intervals, since substantially all of the water is retained in the system.

to just the amount 'of heat desired for maintaining the compartment at a desired temperature. To accomplish this result the valves G and G are automatically controlled by the electrical system shown in Fig. 3. As indicated in this figure of the drawings, the compartment or space is up to the desired temperature and all of the steam flow is directed to radiator F through the open valve G',-the valve G being closed. As indicated diagrammatically in the drawings, each of the similar valves comprises a movable valve member 48 adapted to close the valve passage 49. Valve member 48 is carried by the stem 50 extending from the core of the solenoid motor 52. When the solenoid is energized, the core will be lifted to open the valve, as indicated invalve G. When solenoid 52'is de-energized, the valve will automatically close, as indicated in valve G. If desired, a spring may be used to assist the valve in closing.

The relay R, comprises a movable contact 53 which, when the relay is de-energized, will be drawn by spring 54 into engagement with a fixed contact 55. When the 'coil 56 of the relay is energized, the core 51 will be drawn down so as to pull the movable contact'53 into engagement with a pair of fixed contacts 58 and 59.

The thermostat D is here shown as of the thermometer or mercury-column type comprising the mercury column which will always be in engagement with one fixed contact GI and which will engage a second fixed contact 62 when the desired temperature is reached in the space wherein the thermostat is positioned. The relay R would normally be energized through the following circuit: From battery or other source of power S through wire 63, resistor 64, wire 65, terminal 66, relay coil 56, and wires 61 and 58, back to the battery. However, when the desired temperature has been reached in the compartment, the relay coil will be de-energized since the current will now flow through the shunt circuit extending from one terminal 66 of the relay through wire 59, thermostat contact 62, mercury column 60, contact GI and wires I0 and 68, back to the battery.

When the desired temperature has been reached and the relay R is de-energized, as just described. a circuit energizing solenoid 52 of valve G will be completed as follows: From battery S throu h wires 63 and II. relay contact 53, terminal 55, wire 12, cell 52 of valve G, and wire 58, back to the battery. The valves will now he in the positions shown in the drawings, that is, valve G will be open and valve G closed.

Assuming now that the temperature to which thermostat D responds drops so that mercury column moves down out of contact with the upper contact 62. The shunt circuit will be broken so that relay R will now be energized over the circuit first described, and the motor of valve G will now be energized through the following circuit: From battery S through wires 63 and II, relay contact 53, fixed contact 59, wire I3, coil 52 of valve G, and wires I4 and 68, back to the battery. The valve G will now be open to direct the steam flow into radiator F and heat the air stream delivered through conduitA into the compartment. At the same time the energizing circuit for valve G will be broken and this valve will automatically close so as to cut off the flow of steam to radior F.

While the control apparatus as thus far described would function to alternatively direct the steam from the generator to either-the radiator F or the radiator F', there would be an excessive condensation of steam in radiator F and the compartment would probably be over-heated. This is due to the fact that thermostat D will not function until the desired temperature has been reached in the vicinity of the thermostat, and after the thermostat has functioned to direct the steam into the other radiator F, there will still be a delivery of heat into the compartment from the steam already furnished to radiator F. Preferably an auxiliary electric heater I5 is provided, this heating coil being positioned around or intimately associated with the thermostat. This heating coil I5 will normally be continuously energized through the following circuit: From battery S through wires 63 and I6, adjustable resistor or rheostat 11, wire I8, terminal I9, wire 8|], heating coil 15 and wires 8|, I0 and 58, back to the battery. Assuming, for example, that the thermostat D is originally designed to function at a temperature of 75 F. and the current through heater I5 is sufllcient to add five degrees of heat to the thermostat, the thermostat will new function at a room temperature of 70". By properly adjusting the rheostat II, the strength of the energizing current for heater I5 can be varied so as to select the room or space temperature at which the thermostat D will function.

Assuming now that the temperature within the compartment 3 falls below the desired temperature (for example 70 F.), contact will be broken between mercury column 50 and upper contact 62 of the thermostat D and relay R. will be energized to draw down the movable relay contact 53. This will complete a circuit already described to open valve G and admit steam to the radiator F in conduit, A, but at the same time movable contact 53 will engage fixed contact 58 to add a shunt branch in the heater energizing circuit as follows: From terminal I9 through wire 82, resistor 83, wire 84, relay terminal 58, contact 53, and wires II and 63 to the battery. It will now be noted that the resistor 83 is placed in shunt with the rheostat I1 and as a result the total resistance of the circuit will be cut down so that a greater current will fiow through heater I5. The added heat applied to the thermostat will almost immediately cause the mercury column to again contact with the upper contact 62, whereupon valve G will again be closed and valve G opened. As a result only a short burst of steam will be admitted to the radiator F, even through the temperature in compartment 3 has not yet been raised to the desired level. At the sameltime the shunt circuit through resistor 83 will again be cut out so that the current through heater I5 will again be lowered, and as a consequence the mercury column 50 will again fall to permit another burst of steam to radiator F. If the temperature in compartment or space 3 is far below the desired level, these bursts of steam to radiator F will follow one another rapidly, but when the space temperature is at substantially the desired level these bursts of steam to radiator F will be very infrequent and just enough heat will be delivered to the air stream flowing through conduit A to maintain the space temperature at substantially the desired point. In this way overheating is substantially eliminated.

This heating system is not particularly eflicient as far as the conservation of heat energy is concerned, but this is not important since it is intended for use in connection with internal combustion engines or other installations where the heat used for generating the steam will otherwise be wasted. Heat is constantly being delivered from one or the other of the radiators F or F, but only the desired amount of this heat is delivered into the compartment 3, the remainder being dissipated into the outer. air. The steam heating system is permitted to operate continuously wihout any controls and, therefore, is very simple and effective in its operation. The parts are light and only a small quantity of water is used, which makes the system particularly suitable for use on airplanes where excess'weight must be avoided.

We claim:

1. In a heating apparatus, a closed loop system in which a circulating body-of water is alter: nately vaporized and condensed, said system including a means at oneposition in the loop for continuously vaporizing the water and means at another position for condensing the steam, said latter means comprising a pair of radiators connected in parallel, means for directing the steam alternately into one or the other of the radiators. means for utilizing the heat from the steam condensed in one of the radiators for heating an enclosed space, the heat from the other radiator being dissipated, a thermostat responsive to temperature changes within the space to be heated. an electric heating element associated with the thermostat and adapted when energized to cause the thermostat to function at a lower space temperature, and electrically operated means controlled by the thermostat for automatically causing the steam to be directed to the space-heating radiator when the temperature in the space falls below a predetermined temperature, and simultaneously energize the electric heating element so that the steam will be quickly redirected to the radiator from which the heat is dissipated.

2. In a heating apparatus, a closed loop system in which a circulating body of water is alternately vaporized and condensed, said system including a means at one position in the loop for continuously vaporizing the water and means at another position for condensing the steam, said latter means comprising a pair of radiators connected in parallel, means for directing the steam alternately into one or the other of the radiators, means for utilizing the heat from the steam condensed in one of the radiators for heating an en: closed, space, the heat from the other radiator being dissipated, a thermostatresponsive to temperaturechanges within the space to be heated,

an electric heating element associated with thethermostat, means for adjusting the current normally flowing through the element to determine the temperature at which the thermostat will function, and electrically operated means controlled by the thermostat for automatically caus ing the steam to be directed to the space-heating radiator when the temperature in the space falls below the predetermined temperature, said electrically operated means simultaneously increasing the heat output of the electric heating element so that the steam' will be quickly redirected to the radiator from which the heat is dissipated.

3. In combination with means for providing a constant flow ofsteam, a pair of similar condensers, means for forcing an air stream in contact with one of the condensers and thence into a space .to be heated, means for directing the steam alternately into one or the other of the condensers, a thermostat responsive totempe'rar ture changes within the space, an electric heating through the element to determine the temperature at which the thermostat will function, and electrically operated means controlled by the thermostat for automatically directing the steam flow into the condenser positioned in the air stream whenever the temperature within the space falls below the predetermined temperature, said electrically operated means simultaneously increasing the heat output of the electric heating element so that the thermostat will quickly function through the operating means to redirect the steam flow into the other condenser.

4. In combination with means for providing a constant flow of steam, a pair of similar condensers, means for forcing an air stream in contact with one of the condensers and thence into a space to be heated, means for directing the steam alternately into one or the other-of the condensers, a thermostat responsive to temperature changes within the space, an electric heating element associated with the thermostat and denser.

5. In combination with means for providing .a constant flow of steam, a pair of similar condensers, means for forcing an air stream in heatexchange contact with One of the condensers and thence into a space to be heated, means comprising a pair of alternately energized valveoperating motors for directing the steam iiow alternately into one or the other of the condensers, a thermostat responsive to temperature changes within the space, an electric heating element associated withthe thermostat and adapted when energized to cause the thermostat to function at a lower space temperature, and electrically operated means controlled by the thermostat for automatically energizing one of the motors to direct the steam flow into the condenser positioned in the air stream whenever the space temperature falls below a predetermined temperature, said electrically operated means simultaneously causing the electric heating element to be energized so that the thermostat will quickly function through the electrically operated means to energize the other motor and cause the steam flow to be redirected into the other condenser.

6. In combination with meansfor providing a constant flow of steam, a pair of.similar condensers, means for forcing an air stream in heat-. exchange contact with one of the condensers adapted when energized to cause the thermostat sociated with the thermostat, means for adjusting the current normally flowing, through the element to determine the temperature at which the thermostat will function, and electrically operated means controlled by the thermostat for automatically energizing one of the motors to direct the steam flow into the condenser positioned in the air stream whenever the space temperature falls below the predetermined temperature, said electrically operated means simultaneously increasing the heat output of the electric heating element so that the thermostat will quickly function through the operating means to energize the other motor and cause the steam flow to be redirected into the other condenser.

- 7. In combination with a pipe through which passes highly heated fluids, a generator closely associated in heat-transfer relation with said pipe so that water introduced into the generator will be vaporized, a pair of radiators, a supply pipe leading from the generator and having branches leading to each radiator for conducting steam thereto, means for directing the steam alternately through the branches to one or the.

other of the radiators, a conduit system comprising discharge pipes leading from each radiator for returning the condensate to the generator, a pair of conduits in which the radiators are respectively located and through which air is forced, one of the conduits leading into a space to be heated and the other conduit leading to the open air, a thermostat responsive to temperature changes within the space to be heated, an electric heating element associated with the thermostat and adapted when energized to cause the thermostat to function at a lower space temperature, and electrically operated means controlled by the thermostat for automatically causing the steam to be directed to the space-heating radiator when the temperature in the space falls below a predetermined temperature, and simultaneously energize the electric heating element so that the steam will be quickly redirected to the radiator from which the heat is dissipated.

8, In combination with a pipe through which passes highly heated fluids, a generator closely associated in heat-transfer relation with said pipe so that water introduced into the generator will be vaporized, a pair of radiators, a supply pipe leading from the generator and having branches leading to each radiator for conducting steam thereto, means for directing the steam alternately through the branches to one or the other of the radiators, a conduit system comprising discharge pipes leading from each radiator for returning the condensate to the generator, means for utilizing the heat from the steam condensed in one of the radiators for heating an enclosed space, the heat from the other radiator being dissipated, a thermostat responsive to temperature changes within the space to be heated, an electric heating element associated with the thermostat, means for adjusting the.

current normally flowing through the element to determine the temperature at which the thermostat will function, and electrically operated means controlled by the thermostat for automatically causing steam to be directed to the space-heating radiator when the temperature in the space falls below the predetermined temperature, said electrically operated means immediately increasing the heat output of the electric heating element so that the steam will be quickly redirected to the radiator from which the heat is dissipated.

9. In combination with a pipe through which passes highly heated fluids, a generator closely associated in heat-transfer relation with said pipe so that water introduced into the generator will be vaporized, a pair of radiators, a sup ly pipe leading from the generator and having branches leading to each radiator for conducting steam thereto, means for directing the steam alternately through the branches to one or the ing steam to be directed to the space-heating ,at the thermostat falls below a predetermined other of the radiators, a conduit system comprising discharge pipes leading from each radiator for returning the condensate to the generator, a pair of conduits in which the radiators are respectively located and through which air is forced, one of the conduits leading into a space to be heated and the other conduit leading to the open air a thermostat responsive to temperature changes within the space to be heated, an

electric heating element associated with the 1G thermostat, means for adjusting the current normally flowing through the element to determine the temperature at which the thermostat will function, and electrically operated means controlled by the thermostat for automatically causradiator when the temperature in the space falls below the predetermined temperature, said electrically operated means immediately increasing the heat output of the electric heating element so that the steam will be quickly redirected to the radiator from which the heat is dissipated.

10.'In a heating apparatus, a closed loop system in which a circulating body of water is alternately vaporized and condensed, said system including a means at one position in the loop for continuously vaporizing the water and means at another position for continuously condensing the temperature, and for alternatively closing the first mentioned valve and opening the second valve when the temperature at the thermostat rises above a predetermined temperature.

,11. In-a heating apparatus, a closed loop systemin which a circulating body of water is alternately vaporized and condensed, said system including a means at one position in the loop for continuously vaporizing the water and means at another position for continuously condensing the steam, .said latter means comprising a pair of radiators connected in parallel, a pair of conduits through which air is forced in which the radiators are respectively located, one of the conduits leading into a space to be heated and the other discharging into the open air, electrically actuated valves at the inlets of the respective radiators, a thermostat responsive to temperature changes within the space to be heated, and electrically operated means controlled by the thermostat for opening the valve leading to the space-heating radiator and closing the valve leading to the heat-dissipating radiator when the temperature at the thermostat falls belowa predetermined temperature, and for alternatively closing the first mentioned valve and opening the second valve when the temperature at the thermostat rises above a predetermined temperature.

12. In combination with means for providing a constant flow of steam, a pair of similar condensers, means for forcing an air stream in heat exchange relation with one of the condensers and thence into a space to be heated, means comprising a pair of alternately energized valveoperating motors for directing the steam flow alternately into one or the other of the condensers, a thermostat responsive to temperature changes within the space, and electrically operated means controlled by the thermostat for automatically energizing one of the motors to direct the steam fiow into the condenser in the air stream whenever the space temperature falls below a certain predetermined temperature, and when the space temperature rises above a certain predetermined temperature energizing the other motor to cause the steam flow to be directed into the other condenser.

13. In combination with a pipe through which passes highly heated fluids,a generator closely associated in heat-transfer relation with said pipe so that water introduced into the generator will be vaporized, a pair of radiators, a supply pipe leading from the generator and having branches leading to each radiator for conducting steam -thereto, an electrically-actuated inlet valve in each branch, a conduit system comprising discharge pipes leading from each radiator for returning the condensate to the generator, meansfor utilizing the heat from the steam condensed in one radiator for heating an enclosed space, the heat from the other radiator 'being dissipated, a thermostat responsive to temperature changes in the space to be heated, and electrical-operating means controlled by the thermostat for alternatively and simultaneously opening and closing the valves so as to add heat to the space to maintain a desired space temperature.

14. In combination 'with a pipe through which passes highly heated fluids, a generator closely associated in heat-transfer relation with said pipe so that water introduced into the generator will be vaporized, a pair of radiators, a supply pipe leading from the generator and having branches leading to each radiator for conducting steam thereto, an electrically-actuated inlet valve in each branch, a conduiut system comprising discharge pipes leading from each radiator for returning the condensate to the generator, a check-valve in each discharge pipe for preventing the return of fluids therethrough to a radiator, means for utilizing the heat from the steam condensed in one radiator for heating an enclosed space, the heat from the other radiator being dissipated, a thermostat responsive to temperature changes in the space to be heated, and electrical-operating means controlled by the thermostat for alternatively and simultaneously opening and closing the valves so as to add heat to the-space to maintain a desired space temperature.

- JOHN VAN VULPEN.

PAUL B. PARKS. 

